喷动床内纳米颗粒气固两相流动的数值模拟

采用欧拉-欧拉双流体模型,颗粒动理学理论模拟颗粒相流动,采用周涛和李洪钟(1999)的力平衡模型预测纳米颗粒聚团尺寸,对喷动床内纳米颗粒聚团流化过程进行了数值模拟,得到了喷动床内纳米颗粒聚团的流化过程,获得喷射区和环隙区内颗粒相速度和浓度分布。分析了喷动床结构和进口气体速度等对纳米颗粒聚团流化特性的影响。由于纳米颗粒的特殊性质,不易形成喷泉区。适当的喷动床结构和进口气体速度有助于形成稳定喷动。

NUMERICAL SIMULATION OF GAS-SOLID FLOWS OF NANO-SIZE PARTICLES IN SPOUTED BEDS

Flow behavior of nano-size particles was numerically studied by means of an Eulerian-Eulerian two-fluid model. Particles collisions were modeled by the kinetic theory of granular flow, and the size of agglomerate was estimated by model proposed by Zhou and Li (1999) from force balance acting on an agglomerate. Fluidized behavior of agglomerates was simulated in spouted bed. The distributions of velocity and concentration of particles were obtained in spout and annulus zones of spouted bed. The influence of structure and inlet gas velocity on flow behavior was analyzed. Simulations indicate that the fountain is impossible to form at the bed surface due to special quality of nano-size particles. The proper geometrical of bed and inlet velocity is a critical issue to stable spouting in the spouted bed.